1. Field of Invention
The present invention relates generally to stencil cleaning methods and apparatus, and more particularly to a stencil printer having a stencil wiper assembly designed to enable an operator to quickly replace a used supply of web material, such as a roll of paper, with a new supply of web material.
2. Discussion of Related Art
In a typical surface-mount circuit board manufacturing operation, a stencil printer is used to print solder paste onto a circuit board having a pattern of pads or some other conductive surface onto which solder paste will be deposited. The circuit board is automatically fed into the stencil printer and one or more small holes or marks on the circuit board, called fiducials, is used to properly align the circuit board with the stencil or screen of the stencil printer prior to the printing of solder paste onto the circuit board. Once a circuit board has been properly aligned with the stencil in the printer, the circuit board is raised to the stencil, solder paste is dispensed onto the stencil, and a wiper blade or squeegee traverses the stencil to force the solder paste through apertures formed in the stencil and onto the board. As the squeegee is moved across the stencil, the solder paste tends to roll in front of the blade, which desirably causes mixing and shearing of the solder paste so as to attain desired viscosity to facilitate filling of the apertures in the screen or stencil. The solder paste is typically dispensed onto the stencil from a standard cartridge.
A disadvantage associated with the prior art wiper systems is that the web material supply, i.e., the roll of paper, may be difficult to access and therefore difficult to replace. There is presently a need for a stencil wiper system that enables the operator to quickly and efficiently replace the paper supply upon its depletion. There is also a need for a stencil wiper system that is compact in size, thereby reducing the overall footprint of the stencil printer.